German police fire water cannon and pepper spray at black-clad bottle-hurling demonstrators after Porsche dealership is torched

Hardcore anti-capitalist protesters have been hit with water cannons and pepper spray by German riot police after they attacked officers with bottles and stones at the G20 summit in Hamburg.

Police say they repeatedly asked a group of demonstrators to remove their masks and hoods but instead officers were hit with bottles and bricks - breaking the window of a riot van.

The violence broke out near the start of the demonstration at a riverside plaza used for Hamburg's weekly fish market.

As many as 100,000 protesters from across Europe are pouring into the port city for a demonstration dubbed 'Welcome To Hell'. Police believe as many as 8,000 are ready to commit violence.